Instrument for testing lenses.



0.1. TROPPIVIAN.

.INSTRUMENT FOR TESTING LENSES.

APPLICATION FILED AuG.3|.1914.

l 2l ,7 l '7 u Patented Oct. 15, 1918,

5 SHEETS-SHEET I.

Patented Oct. 15, 1918.

6 SHEETS-SHEET 2.

C. 1. TBOPPMAN. INSTRUMENT FOR TESTING LENSES.

APPLICATION FILED AuG.sI. I9I4. 1928131?,

IQ e I 0.1. TROPPMAN.

INSTRUMENT FOR TESTING LENSES.

APPLICATION FILED AUGJII 1914.

6 SHEETS-SHEET 3.

TAR GE' TIS MM W.

C. 1. TROPPMAN.

INSTRUMENT FOR TESTING-LENSES.

APPLICATION FILED AuG.3I. 1914.

Patented (1ct. 15, 1918.

IIIIHH! I mi f Nad o\ W, f

C. J. TROPPMAN.

INSTRUMENT FON TESTING LENSES.

APPLICATION FILED AUG.3I \9I4.

Patented Oct. 15, 1918.

6 SHEETS-SHEET 5.

C. J. TROPPMAN.

AINSTRUMENT FOR TESTING LENSES. APPLICATION FILED ALIG.3I. 1914.

l ,28 l ,7 l '7. Patented out. I5, IIIIII.

6 SHEETS-SHEET 6. Q mi CHARLES J. TROPPIIAN, or' CHICAGO, ILLINOIS, AssIoN'on 'ro F. A. HARDY e COMPANE,

OF CHICAGO, ILLINoIs, n CORPORATION orl ILLINOIS.

INSTRUMENT FOR TESTING LEN'SES.l

assisi?.

spammen of Letters Patent.- :yfmemd @at 15,' 1mg,

i Application led August 31, 1914. Serial No. 859,317.

dent of Chicago, in the county of Cook and State of Illinois, have invented a new and useful Instrument for Testing Lenses, ofl

which the following is a specification.

My present invention relates to the pro-4 vision of suitable facilities for testing lenses, and the objects thereof are, first, the em- A bodiment of the necessary facilities for -.the light and vform an image.

thoroughly analyzing a lens and ascertain- 'ing its refractive properties in an instru# ment which will beeasy to manipulate and which will have a high degree ofprecision or accuracy; second, the rovis'ion vof such an instrument, which after the same has been adjusted,may be used by comparatively unskilled operatives thereby rendering the instrument useful in the testing of llarge numbers lof lenses in shops and factories.

In the working out of my present invention -I -hav'e endeavored to obviate the error arising from an arrangement in which the lens under examination is caused tol-focalize rangement involves a consideration of the focal length of the lens under examination and the nodal points or centers of refracf tion of the respective surfaces of the lens which, so far as I am aware, with the usual test instruments, if not taken into account,

will result in error. I have also provided means which will permit of the examination ofthe refraction upon one meridian of the lens -andjafter the instrument has been adjusted for that meridian another meridian may -be examined without disturbing the rst adjustment. These facilities are particularly useful in the examining of lenses of the optical center is ascertained by the positioning of the lenses` to be tested instead of the measurement-of refraction which the decentering causes. This I believe is amore direct and accurate arrangement than has heretofore been employed.

I have also introduced a possibility of adjustment with respect tothe standard lens which renders it possible to adjust the focal y.length of the 'standardlens accurately to :the scales upon the instrument. I have also Such an arf-- I have also ar-l provided, so far as I am aware, a new and desirable 'means for certainly locating the lens I .have -attained v the above objects by means of the mechanism illustrated in the accompanying drawing in which:

Figure 1 isa longitudinal elevation-of the instrument which is the subject-.matter of:

the .present specication. Fig. 2 is an elevation of the instrument looking vfrom the operators end;

I Fig. `3 is a yertical -transverse section on l1ne 3--3V of Flg. l', looking from the operators end;

Optical axis of the instrument;

. Fig. 5 is a schematic view oflthe optical elements of the instrumen-t;

Fig. 6 is a detail elevational view of the mechanism for. holding and 'moving the lenses to be tested and the dial for show-ing the'meridional dispositions of the test lines of the targets.

" Fig. 4 isa horizontal section through the Fig. 7 is a detail partially in section of I tion ofthe vertically .movable lens holding carriage and' a. section on line 13-13 thereof;

Figs. 14 and 15 are respectively an elevation of the horizontally movable lens holding carriage and a -section lon line 15-15 thereof;

Figs. 16 and 17 are re'spectivelyanA elevation of the lens holding members'and a sec- Fig. 18 is a setion on Vline 18--18 of Fig. 12;

Fig. 19 is asection view through the llens holding mechanism assembled on line `119--19 of Fig. 6, and

Fig. 20 is .a fragmentalfdetail in plan of the means for mounting the vertically mov 'able carriage.

Similar reference characters refer to similar parts throughout the several views.

' Itis thought that the invention can best be considered by first discussing the optical arrangements thereof vandthe objects to be accomplished thereby, and then proceed to a description of the mechanical facilities by means of which the desired optical conditions are secured and the requisite movements of the optical elements are effectuateil. Reference should therefore first. .to be had to Fig. 5.

The optical action of the instrument originates at the source of illumination. Any

. suitable means may be employed for furnishing the necessary amount of light. An incandescent electrle bulb isa very convenient means of illumination, and .when such a bulb is employed lit is desirable to have conmoving the targets along vthe optical axis of' the instrument and for moving one of the targets independently of the other. Facili- .ties 'are also provided for rotating the tar- ',-gets independently'of the longitudinaladjustment so as to dispose the lines thereof in any meridian of instrument.

' Scales are provided in connection with the facilities for moving' the targets longitudinally, the zero point upon which indicate brought into substantiall the same-plane, and positioned its focal vength away from the targets, when brought substantially in the same plane and at the zero point of their scales, is a standard lens.v lThe standard lens is preferably formed ofla plurality of elements divided by an air space, and

means, hereafter to be described, 'are provided for increasing or decreasing this air space for the urpose of accurately adjusting the focalV ength of the combination.-

It will now be seen that when the-targets i i are a focal length distant. from the standard lens, or in the plane of its equivalent focus, light proceeding .from the targets tothe standard lens will, as the phrase goes, be

focused at infinity or be parallel -or be as if it proceeded from an object at a great distance. A

Means, also hereafter'to be described, are

provided for supporting the lens to be tested the field of vision ofthe' in the plane ofthe equivalent focus bf the standard lens opposite to the normal or-zero location of the targets.

It will now be appreciated, that light reaching the plane of the location of the lens to be tested from 4the .targets through the standard lens will be regularly modified or refracted in the .proportion that the distance the targets are moved from normal position bears to the focal length of the standard I llens.

That is to say, if the .standard lens is a ten centimeter lens and the target is moved one centimeter farther fromA the standard lens, the image ofthe .target would.

be focalized by the. standard lens Aat ten tiines the focal length of the standard lens'A from its opposite equivalent'focal plane, or one hundred centimeters or one meter therefrom. Or, at the plane ofthe equivalent focus of the standard lens the light would be 85 converged one tenth of the hundred centimeters, 4or the amount which it would be converged bya -lens of one hundred centii eters or one meter equivalent focus. This relation is constant andeifects a. divergence of the light upon the same principles when the targets are brought between the plane of the equivalent'focus and .the standard lens, and when the scales showing the movementv of the targets are provided to' 95 show this'movement in terms of the focal length of the standard lens the scales will showthe amount ofrefraction which is secured by any particular adjustment of the targets. With a lenstobe tested in position, adjustments may be made to overcome the refraction of the lens so that the light" will leave it in normal condition or without `convergence or divergence and the amount of the adjustments to secure this 1.05'

condition will show the power of the lens -to be tested. a normal position for the targetswhich willproduce no -correction. The targets 'may `be v So far as I am aware lenstesting instru- 4ments hitherto have been constructedso as to cause the lens to be testedto focalize the 4image or to form a real image thereof. With such a construction error is liable to occur as the formation of such an image involves the focal length 'of the lens measured fromthe optical center of the lens which 1-15 bears -a definite relation to the nodal points or centers of. refraction of the respective surfaces. .TheseI nodal points are diflicult to ascertain and to pr perly locate after they ment-just described in which the. refraction of the`lens to be tested is neutralized and the light' leaves the lens to`be tested in normal condition free from convergence or diverormation of the 'mage'thereby.

. It will also be vseen that when the lens to .be tested has a. cylindrical elementthe targets mayfbe rotated to bring the lines on one of. the targets in the meridian of.130

`have -been ascertained.. With the arrangeence no error. arises withreference to the mami? lenses of any degree of complicationhand4 then a comparatively inexperienced operator, such as must be employed in factories and shops, can run through any quantity of lenses to see whether they conform to the particular requirements of the adjustment.

In order to ascertaimwhether' the refrac` tionof theulens'fto be tested has been accurately neutralized,- I have employed a focalizing or'imageforming lens which will form an imageof parallel light, or light free from convergence or i divergence, upon a\ screen located at a "suitable distance therefrom and I have provided an eye piece by means of which the image formed on the screen inay be critically examined.

It will of course be apparent that the mechanical embodiment of a device for realizing the v'advantages of the application of principles of optics must be more or less approximate and that the degree of approximation is, to an extent, optional and that approximations can easily be made which will secure those advantages to asulicient degrec' for all practical purposes. Forminstance, the test lensmay be displaced slightly from the plane of the principal or equivalent focus ofthe standard lens, and the departure ffro'm a uniform scale necessitated thereby will only be so," slightthat all the practical advantages` of""such a scalev will be retained. Also,y the image screen may be' displaced fronrthe plane of the principalor equivalent focus ofthe image 'forming lens to such a slight extent that theresultant bending` of the rays leaving the lens under test to cause them to begfocused on the screen, would be so slight that the position of the nodal point of the emergent surface of any ophthalmic lens would be entirely negligible and I desire it. understood that any such i deviations from the theoretically indicated p movements above referred' to are as fol-v points are contemplated as included within thel scope of my claims. v

The mechanical features of the instrument for securing thel optical conditions and lows The instrument is the instrument stability. .Arising from the foot or claw, A, is a cdlumn or standard, B,-

swung at any angle preferred bythe oper-l ator for making the examination.

The pivoted frame C comprises a table or -mounted upon afstandv comprisinga' heavy foot or claw A to give arm C1, extending from above the column or standard B, in a direction alining with the parts of the frame which extend into the C2 is turned upward and extends farther outwardly so as to furnish a long and rigid bearing for the mounting for the viewing lenses and also to bring the viewin lenses in alinement with the source of ilumination. The standard lens and the lens hold: ing means are mounted upon or secured to a .plate E disposed transversally and secured' to the inner end of the table C1.

The details of the mounting of the eleci' tric bulb which comprises ,the means ofillumination illustrated in the Fpresent application are clearly shown in lgs. l .and .l, land consist of a bracket, l, screwed or other-N wise secured'to the outer end of the table C1. Upon the-top of the bracket, 1,- i's secured'a tube, 2, into the outer end of which extends the tubular flange, 3, of a ca'p 'member, 4f,v in the center of which is secured an electric bulb socket 5, into which screws an electric bulb, 6, of a 'suitable size and character. Into the opposite end of the tube, 2, is screwed or otherwise secured a lens cell in which are mounted suitable condensers or paralleling refractors, 8. n

The details of the mounting for the targets Y are shown in Figs. 1 2, 3, 4, 7 and 8. y lTheftop of the table C1 1s longitudinally slotted or channeled, as clearly shown in Fig.

3, and lfor the purpose of securingajfree f the vertically converging walls 9. Just be low the converging portlon of the walls the slot 'is laterally extended to form a rectangular channel, 10 for the carriage retaming plate and below and in the center of the retaining plate portion of the channel and f communicating, therewith there is a vertical l groove, 11, which forms away1 and housing for the' carriage rack. At a' suitable point,

12, longitudinally of the tablev G1 the groove 11 is carried through the bottom ofthe'table and at this point is mounted, upon an arbor, 13, extending transversely @of the table, a gear, 14, the teeth of which extend upwardly soas to engage the rack of the target car- Y ria'ge housed in the groove, 11. Upon the outer end` of the arbor, 13, is mounted a hand lwheel or head, 15 which has a disk, 16,/of

.much larger diameten integral therewith,

the edge 17 of which is turned laterally to form a cylindrical area of sufficient extent to receive a scale 18 showing the extent of longitudinal movement of the ,targets carried by the carriage.

The main part of the carriage, 19,' is a sub'- stantially rectangular block of a suitable size from the bottom of which projects a rail, 20, formed to correspond with the converging walls 9 of the channel in the table C1. To the bottom of the rail 20, are screwed the retaining plate, 21, and rack, 22, fitting Within respectively the rectangular channel, 10, and groove, 11, of the table.

The upper face of the main part of the carriage 19, is slotted longitudinally precisely asis the table C1, to receive a converging rail 23, retaining plate, 24, and rack, 25, of an 'auxiliary carriage 26, which is moved longitudinally by a gear, 27, carried on an arbor. 28, mounted transversally of the mainl part of the carriage, 19, 1n a manner similar to like parts for moving the main portion of the said carriage.

The arbor, 28, is also provided with av head, 29, which hasl afscale 30 thereon for the purpose of showing the extent of longitudinal movement of the target carried by the auxiliary carriage, Which head and scale are similar to the head, 15, and scale 18 of the main portion of the carriage. The above described arrangement Will permit of the longitudinal movement of the main part of the carriage, 19, and the auxiliary carriage, 26, simultaneously by turning the head, l5, while the auxiliaryI carriage may be moved independently of the main part of the carriage by rotating the head 29.

Upon the top and adjacent one end of thev auxiliary carrlage, 26, is secured a barrel, 31, within which is rotatably mounted a tube, 32, having an annular flange, extending outwardly or laterally therefrom, the periphery whereof is provided with the gear teeth, 34.

Mounted Within the end of the tube, 32, and so as to rotate ltherewith is a comparatively short tube, 40, within and adjacent the inner end of which is mounted one of the targets, 41. Another but somewhat longer tube, 42, slides or telescopes within the tube 32, so that its inner end may be brought adjacent the inner end of the tube, 40, and adjacent thev inner end of the tube, 42, 1s

mounted another target, 43. The outer end v of the` tube, 42, is provided with an ont- Wardly extending annular flange, 44, which lits within an annular groove or depression,

spect to the plate, 47, by means of the ring shaped plate, 48, screwed to the plate, 4'?,

so that its ,inner edge extends over the flange 44 and the groove 45. A spline, 49 is provided longitudinally of and uponl the inside of the tube 32, which fits within a splineway, 50, provided upon the outside and longitudinally of the tube. 42, so that while the outer collar, 31, and the tube, 32, and tube 40 seen that the targets 41 and 43, may be moved longitudinally simultaneously by :i

rotation of the head, 15, that-the target, 4l,

may be moved longitudinally independently of the targetY 43 by a rotation of the head 29; and that both targets may be rotated s' simultaneously in any longitudinal position in which they may be adjusted.

For the purpose of readily rotating the targets through the instrumentalities just described and also for indicating the meridians of the field of vision in which the lines of the targets are disposed I have providcd the following mechanism: The plate E is screwed or otherwise secured to the in* ner end of the table portion (l1 of the frame C so as to extend transversely of the frame C and upwardly beyond the optical :mi the instrument 1s an aperture El. ln troni' of the plate E, or on the side thereof *facing the operator, is provided a groove or del v. r

pressed area 51, which is concentric with the aperture E1 and is separated therefrom b v the annular shoulder, 52, which shoulder is exteriorly threaded. Fitting within the depressed area, 51, is a dial 52a which is held in position by the flanged eentralljY bored and threaded bushing, 53, which screws upon the annular shoulder 52, and the flange whereof fits within a channel, 54, provided in the face of and adjacent to a central aperture, 55, in the dial through which extends the said bushing, 53.

At the rear 'of the depressed area, 51, communicating and concentric therewith is a further depressed area, 56, of a lesser diameter than the area, 51, into which extends a dlsk, a7, made integral with or secured to the dial, 52, which said disk, has provided on the edge thereof gear teeth, 58. Also to the -rear of the depression 51 is a smaller circular depression, 59, which alines with and slightly overlaps the depression, 5G, so

lli-

lilo

that the teeth of the gear wheel, 60, housed in said depression, 59, will mesh with the teeth 58a upon the periphery of the disk, 57.

The metal of the plate E is bored through' centrally and back of the'depression 59, at

.61,-to permit of the passage of the .rod'

which extends parallel with the path of longitudinal travel ofthe main and 'auxiliary carriages, 19 and 26. A bushing 63 a reduced portion 64, of which has a .frict1onal is provided with a spline-way or feather-A 4way, 65.

Upon the side ofthe collar, 31, adjacent the rod 62 is provided a bracket, 66, within which is a suitable bore, 67, in which is ro` tably mounted the flanged sleeve 68, through the central aperture, 469 of which passes the rod, 62, and which is provided with a' spline or feather 70 which-'extends into the splineway or feather-way 65 of the rod, 62. Upon the portion of the sleeve, 68, which-extends out ofits bearing 67, in the bracket, 66, is secured a gear, 71,'which meshes with the gear teeth, 34, upon the annular flange, 33, of the tube, 32. i

The edge of theface of the dial, 52, is pro- Y vided with a suitable scale, 72, which copl ,erates with a line, 73, upon the face of-the plate E toindicate the-meridian in which the holding means comprises a plate, 92, of right lines of the target have been adjusted.

It will now be seen that' a rotation of the knurled linger wheel 64a will rotate the targets simultaneously in any position in which they may be positioned longitudinally and will at thel same time indicate through the rotation of the dial 52 in what vposition the lines f the targets are brought-by such rota, tion.

The standard lens and itsl mounting and also the means for securing the lens to be tested 'are both carried by or 'secured to the lower lens holding and centering members,

plate E. v

The-mounting for the standard lens isas follows z-About the edges of the aperture El, and upon the side of the plate E facing the targets, is provided an annular laterally extending flange E2, which together with the aperture El is interiorly threaded to receive the exteriorly threaded end'of an interiorly threaded collar, 74, into the respective ends of which are screwed mountings 75 and 76, for the respective the standard lens. l A

It will now be seen that an adjustment of the lens elements 77 and 78 is possible .by

means of which-the air space between them may be increased or diminished, therebv increasing or diminishing the focal length of the combination. v

4-Adjace'nt the face of the plate opposite to thestandard Alens is disposed the -means for securing the lens to betested, the struc- .ture of which is illustrated in detail in Figs.

1, 2, 4, 5, 6, and 11-to 19 inclusive to which particular reference may be had. To the back and edge of the plate E is seelements 77 and 78 of,

cured, by-means of screws or otherwise passlng through the ears or lateral extens1ons,

79, the vertical plate'80, illustrated respecslides the T rail 82 located upon the back of the vertical member 83 of the l. shaped ver-l tically movable carriage illustrated in Figs. 1 2,- 13, and 18. The vertical member 83, is 75 V provided with an interiorly threaded transverse bore, 85 to receive a set screw 86, byv means-of which the vertical carriage may be secured in any desired position. The horizontal member 84, of the vertically movable carriage 'comprises two plates 4secured together'by suitable screws and in these plates and opening at 'theadjacent upper edges thereof is provided the under-cut channel,

87, with the rectangular channelI rack hous-Jl 85 ing `88, inthe bottom thereof -as clearly shown-in Fig. 18. -The plates forming the horizontal-member 84v are further bored transversely at 89 to receive the knurled headed arbor, 90 upon which is mounted a gear, 91;, the teeth of which extend into the rack housing, 88, as shown in Fig.- 19. The horizontally movable carriage 0f the lens angled section as shown in Fig. 15, upon th 95 lower face of the horizontal flange ofwhich is provided a V sectional rail, 93', on the botof the vertical flange of the lhorizontally movable'carriage plate 92 are two parallel horizontally disposed T .section rails, 95,v upon which are mounted the upper and 96 and 97, the rear faces of which-are provided with T' sectionslots, 98, adapted to,

assemble with the rails 95, aforesaid. The upper lens holding member, 96 has at one 110 end aftrans'versely disposed arm 96, and

.the lower rlens holding member, 97, is provided with a laterally extended arm 97^- which comes opposite the transversed arm 9 6A of the upper member. These arms 964 115 and'97A are provided with' laterallyl extend-1 ing pins 99, which are adapted to contact with the periphery and center lenses the edges of which have been symmetrically shaped. The 1e holding members are moved simultaneousl'y so as to separate or bring the arms. 96A and 97A closer together -through the instrumentality of the racks 100, provided on the facing edges.. of the portions of'members 96 and 97 which enga-ge the rails 95. The said racks, 100 being engaged by a gear, 101, the centralportion 102, of which is 'bored to receive the stud or arbor, 103 one vend of which is secured in any suitable manother end is bent to enter a bore, .107, in the v plate, 92.

The action of the spring is to rotate the gear so as to normally hold thearms 96A and 97 A closest together. The arms l96" and 97A are separated for the purpose of receivin lenses through the following instrumen- The side'of the gear opposite the annular chamber, 104, is reducedv and threaded to receive the arm, 108, Which is held in position by the retaining or lock nut, 109. The

entire gear construction is held in position upon the arbor, 103, by means'of the screw 110 which enters a'screw hole, 111, tapped into the top of the arbor for its reception.

For positioning the lens to be tested the proper distance from the standard lens, heretofore described,I have provided a piece of tubing, 112, of suitable length which is screwed into the aperture E1 in the plate E, and which extends between the arms 96A and 97A of the lens holding mechanism, and in the outer end of the tube 112 is mounted .the cross, 113, the arms of which` are -laterally extended and have their outer edges curved backwardly, as shown in Fig. 8 so that the center of said cross can be brought against the center of either a convex or concave lens. The lens holding means heretofore de'- scribed are suitable for cut or shaped lenses, or lenses which have a symmetrical outline.; When it is desired to examine an uncut lens with an irregular outline, the set screw 86 is loosened and the vertically movable carria ev is permitted to descend until it is out oft e way of the opening of the tube 112 and the Encit lens is held against the cross 113 by I have provided upon the back of the plate E a sprin arm, or latch, 1-14, the lower end of which 1s bent at 115 toengage the verti' cally movable carriage when the mechanism isin proper position to center vertically a symmetrical lens held by `the pins, 99, so that after examining an uncut lens thelens holding carriage may be brought into proper osition by merely elevatmg the.. vertic ly mounting for the viewing lenses'.

movable carriage until it is engaged. by the spring arm, 114.

Suitably secured to the arm -Czfof the frame C 1s the telescope or arran ement or 's telescope comprises a tube, 116, in the inner -end' of which 1s mounted an objectivelens, 117, capable of focalizing Vparallel light, l or light which is neither converged or diverged, upon' 'a suitable screen 118 mounted and adj acont-the opposite end of said tube, 116, and' fitting within' the Itube 11-6 adjacent. the screen 118 is a suitable eye-piece, V119, for

magnifying and viewing the image formed prising means for locating a lens to be ex` amined, a standard llens located the focal length of said standard lensfrom the lens to be examined,.targets upon the. opposite s ide o f saidstandard lens, and means for-moving said targets simultaneously and one of said targets independently longitudinally of and in the optical axis of said standard lens.

2. An instrument for testing lenses comi -prising means for locating a lens to be examined, -a standard lens located the focal length of said standard lens from the lens to be examined, targetsupon the opposite side ofv saidstandard lens, and means for moving said targets simultaneously and one of said targets independently longitudinally of and in the ofptical axis of said standard lens, and means o r rotating said' targets.

3.. An instrument for testing lenses com# prising. means for vlocating a lens to be examined, a standard lens located 'the focal length of said standard lens from the lens to be examined, targets upon the opposite side of said standard lens, and means for moving said targets simultaneously and one ofsaid targets'independently longitudinally of and in the o tical axis of said standard lens, and

means or simultaneously rotating said targets independently :of their longitudinal adjustment.

4. In an o tical instrument, a standard lens, and indiependent targets disposed in different meridians and movable in and longitudinally of the'optical axis of said standard lens. i

5. In an optical instrument, a lens, targets 4 disposed in different meridians and movable simultaneously and `independently in and longitudinally of the optical axis of said' lens. i 6. In an Voptical instrument, a standard lens, and targets disposed in different me ridlans and movable in ,and longitudinally of the optical axis of 'said standardlens, and scales showin the amount of movement of' said targets om'the plane of equivalent focus of said lens, or fromA each .other in terms ofthe 'uivalent focus of said lens.

7 In an optical instrument, a lens, targets adapted to e illuminated by transmitted light disposed in different' meridians and.

movable -simultaneously and independently 1n. cand longitudinally of. the optical axis -of sai 8.- In an optical instrument, alena, targets adapted to be illuminated-by transmittedl light disposed in different meridianar and 4movable simultaneously and independently in and longitudinally of the optical axis of ysaid lens, and wmeans for rotating said tai'- gets independently lof their longitudinal disposition. l

9. In an instrument for testing lenses having a standard lens, means for locating ay lens to be tested a definite distance from said 'standard lens comprising a cross with lateraway upon one side so as to leave the point f of intersection extended and free to Contact v the surface of a lens.

1l. In an instrument for testing lenses,

Yhaving a standard lens, means for locating a f lens to be tested comprising a member hav'- ing apertures therein for the passage ofthe light, said member being adapted to be disposed in the path. of light and having a point extended and located in the axis of the pathI of light adapted to contact the surface of a lens.. Y 3 12. An instrument for testing llenses comprising means for' locating' a lens to be exL amined, and means for neutralizing the refraction of said lens comprising a standard lens located the focal length of said standard lens from the lens to be examined, anda target upon the opposite side and movable longitudinally of and in the optical axis of said standard lens, and a focalizing or image forming lens and a translucent screen for receiving the image formed by said'lenslocated in the plane of its equivalent vfocus. v13. An instrument for testing lenses comprising a principalor standardv lens, a target movable longitudinally of and in the optical axis of the said principal lens, sca1es for showing the extent of.y movement of said .tar-

vwy e? scribed, the combination with a positive lens -and an illuminated diagram, of means for varying the optical power of rays of light,

radiant from said illuminated diagram, in-

cident 'upon a lens --under test, to thereby compensate'for thevoptical' power of said 'lens under testby causing the rays of light i to enter said positive lens parallel.

16. In anA instrument of the class described, the combination with a positive lens and means for viewing an image formed at its principal focus, and-an illuminated diagram, of a support for a lens to be tested,

between the said positive lens and the illumiv l -nated diagram, and means for varying the separation between the illuminated diagram and the lens under test for the purpose of Varying the optical power of light incident upon thelens under test, to thereby bring the rays delivered from said lens un- ,dertest to said positive lens `into parallelism.-

17.' In an instrument of the class described, the combination with a positive lens and means for viewing an image formed at its principal focus and an illuminated diagram, ofa support for a lens to be tested between said positive lens and the illuminated diagram, a lens system interposed between the illuminated diagram and the lens to be tested, and means for varying the optical power of light delivered by said lens system to the lens under. test to thereby cause rays of light radiant from said `illuminated diagram t0 emerge parallel from the lens under test, and thus secure parallel vincidence at said positive lens. l i l 18. In a positive lens system of' which the lens under test forms a component part,

means for supporting the lens under test, a diagram screen and means for adaptin said screen to the position of the principa -focus of said lens system, a scale for indicating, in terms .of the optical power of the lens under test, the position of said screen relativeto said lens system, a positive lens facing said lens sysjtemand adapted to'form an image oflsaidvdiagram at' its principal focus, means for illuminating said diagram screen, and means for viewing the image of said diagram screen formed at the principal i get from the plane of the equivalent focus of .focus of said positive lens.

19. In an apparatus of the class described, y

4cipal focus of said principal lens. opposite to the path of movement of vsaid target.

141.. In an optical instrument,a standard lens, and separate targets disposed in diiier-` ent meridians and independently movable in a flens, a'translucent screen placed at the principal focus of said lens, a lens system facing said lens, a diagram, means for mov-- ing said diagrani relative kto'said lens system, means for holding the lens under test between said lens' andA said lens'system,means for illuminating said diagram, and means for viewing the image of said diagram and longitudinally of the optical axis of said ,formed on said translucent screen.

. targets.

standard lens and means for rotating, said l 15.1In' an instrument fof tlie class cle` 20. Inan apparatus of the class described, the combination of a positive lens and a positive lens system facing each other, said. lens system ineiudin a lens under test, an object, said object eing so related to saidr lens system that when the objectis placed at the principal focus of said leds system its image -will be formed at the principal'focus of said lens, means for viewin saidima'ge, the po- `sition of the plane of t e principal focusof said lens systembeing a measure of the opticalpower of the lens under test.

21. In an apparatus of the class described,

a lens, a translucent screen placed at the principal focus of said lens, a lens system facing said lens, a diagram,omeans `for holding the lens to be tested between said lens Aand said lens system, means for moving said diagram relative to said lens system, a scale for indicating, in terms of the optical power of said lens under test, the position of said diagram relative to said lens system whereby parallel rays emerge from said lens under test, means for rotating said diagram about the optic axis, a protractor for indicatin the extent of said rotation, means for illuminating said diagram, and means for viewing the imageof said diagram formed upon said y Y translucent screen. y

22. In an apparatus of the class described, a positive lens system of which the lens under test forms a component part, means for supporting the lens under test, a diagraml screen and means for adaptin said screen to the plane of the-principal 'ocus of said lens system, a scale for indicating, in terms of the optical power of the lens under test, the position of said screen relative to the position of the plane of the principal focus of said lens 'system when the power of the lens under test is zero, means for rotating said diagram screen about the optic axis, a

protractor for indicating the extent of said rotation, a positive lens facing said lens system andl adapted to form an image of said diagram screen at itsvprincipal focus, means for illuminating said diagram screen, and

ber 'being disposed in the path of light and adapted to contact the surface of the lens to be tested.

24. An'instrument for testing lenses coin- 'prising means for locating a lens to be examined, a scale disposed parallel to the optical axis of said lens, a target movable longitudinally with respect to said scale, a standard lens comprising a plurality of lens "elements located'midway between said lens locating means and the zero point upon said scale, andmeans for adjusting said lens elements so as to make the equivalent focal length of said standard lens equal its distance from said lens locating means and said zero points.

25. An instrument for testing lenses comprising means for locating a lens to be examined, and means for neutralizing the refraction of said lens comprising a standard lens located in a plane at a distance approximately the focal length of said standard lens from the lens to be examined, a target upon the opposite side and movable longitudinally of and in the optical axis of said standard lens, a focalizing or image forming lens, and means for viewing the image formed thereby at approximately the plane of its principal or equivalent focus.

In testimony whereof I have hereunto set my hand in the presence of two witnesses.

CHARLES J. TROPPMAN.

1Witnesses:

E. O. TROGER, BENJ. T, RooDHoUsE. 

